Cafepress

Sand Beds

Greetings folks. Thank you for joining in on the talk abut sand beds. I
would like to begin by saying that I will probably deviate quite a bit from
what most may be thinking this talk will be about.

I will NOT be discussing NNR systems, or plenums, and sand beds for
filtration, etc. This material is commonly available all over in books, and
on the net. Frankly, there is little I could add, and I really don¹t
subscribe to many of those thoughts anyhow, and shortly you will see why
:-)

What I WILL discuss has to do with sand beds in nature. The reason why I
feel this is critical to our success as aquarists, is that we try to
duplicate a portion of nature in our tanks. In order to successfully
accomplish this feat, we must all understand better the processes involved.
In order to best present this information, I would like to offer a few
definitions of terms that I will be frequently referring to.

Infauna - Animals that live within sediments on seafloor bottom.

Epifauna - Benthic animals that crawl along the bottom or are firmly
attached to bottom structures.

Macrofauna - Macroscopic animals that live on or in sediment.

Microfauna - Those animals less than 50 microns that live within
The sediments.

Meiofauna - The animals between sizes. Also between spaces- these
animals live within the interstitial spaces of the sediments.

Closed System - System which has no connection with outside environment.
A typical home aquaria.

Open System - A system with a direct interchange with the outside
environment.

So, I believe we are ready to begin. :-)

SeaFloor Characteristics

Seafloor characteristics are a crucial part of the habitat of benthic
organisms. As the substrate supports the weight of many animals
considerably more dense than seawater. It also allows a place to
construct burrows, tubes, or secure firm attachment to.

The seafloor also acts as a mechanical barrier to collect and accumulate
plankton, waste material, and detritus. A variety of worms, echinoderms,
mollusks, and crustaceans obtain their nourishment from this organic
matter.

Benthic organisms are adapted for a particular bottom type; and
character of life there, to a large extent, is dependent on the properties
of bottom substrate. This bottom material varies from very solid rock to
very soft, loose deposits. The actual composition of the seafloor is
determined principally by the amount of energy available. In nature this is
through wind driven waves primarily. In an aquarium, it can be from
the use of auxiliary pumps.

Benthic animals play an important role in mixing and sorting of
sediments by their burrowing and sorting of the sediments by their
burrowing and feeding activities. Oxygen and water from the sediment
surface are transported down into the sediment through these tubes and
burrows Further modification of sedimentary characteristics is
accomplished via cementing particles together to form tubes, and by
compacting sediments together as fecal pellets and castings.

The distributional patterns of benthic animals and plants are strongly
influenced by the form and texture of their substrate. These factors
determine effectiveness of locomotion, or for non motile species, the
persistence of attachment to bottom. So, what does all that mean for
the home aquarium? I hope I have illustrated how important a role sediments
of any type play in nature. It provides nutrients, serves as a
habitat. It also acts as a source of minerals- more on this later. In
our aquaria, it serves all these functions, plus adds a decorative flair to
the overall appearance of the tank.

Animal Substrate Interaction

Because of the different distributions, unique adaptations have
developed allowing for specialization to those environments.
The particle size and organic content of the bottom material limits the
versatility; and thus the distribution of specialized feeding
habits.

Before you say huh?¹, allow me to explain in terms of our captive
closed systems. All the diverse habitat types in nature all support a
selective array of animal life. What exists in one biotope, most probably
will not exist in another. In our aquariums, this translates well into the
discussion of live rock and live sand.

Live rock is a solid substrate. It has a variety of live within and
about it. From small sponges, tunicates, to corals. Within may be alages,
bacteria, and more. All of these animals and plants have adapted to life on
a hard substrate such as the live rock. Sand on the other hand is a totally
different environment. It is much softer, and will not offer the same
advantages to most of the animals

Yes, some will be able to make the transition, and tolerate the new
habitat, but many will not migrate to the new habitat. Hence the reason why
adding live rock to dead¹ sand will not ultimately lead to a live sand
bed.

Before the critics jump up and yell, let me explain my opinion of live.
Yes, the sand will have life in it. But will it have the typical life found
within that format of sediment? No. It has to come from somewhere,
and sand animals and plants as a rule don¹t live on rock, and vie
versa.

Suspension feeders depend on small plankton or detritus for
nutrition. Filtering devices or sticky mucous nets are employed to
collect minute suspended food from the water. Suspension feeders generally
require clean water to prevent accumulation of indigestible particles.

Deposit feeders engulf masses of sediments and process them through
their digestive tract. They extract nourishment through their
digestive tract from the organic matter of the sediment in much the same
manner as an earthworm.

If we are to keep obligate suspension feeders, or deposit feeders in our
aquariums, we must be sure to provide them the proper and suitable habitat
to thrive in.

To further discuss sediments I need to again clarify some vocabulary.
Sediment size is discussed as the size of grains. These range from
boulder size grains¹ that are greater than 256 millimeters, to silts and
clays which are a minuscule 0.0004 millimeters. Sands fall in the
middle with coarse sand being 1 to 2 millimeters, and fine sands (oolitic
sand) being 0.25 millimeters or smaller.

For a further discussion on sediment sizes, and types, please see June
1998 FAMA, and July 1998 FAMA for the article I co-authored with Eric
Borneman. It contains many relevant diagrams and charts that will
allow a better understanding of today¹s chat. This process is called
sediment sorting.

Many reef sediments are terigenous in origin (in Atlantic reefs).
Terrigenous sediments are those originating from terrestrial origins, and
entering the ocean through streams and rivers.

The Atlantic Ocean has more large volume rivers that dump literally
millions of cubic feet per hour of terrigenous sediments into the
oceans. Much of this falls along the Continental shelf, but some does
reach the reef zones.

In the Pacific Ocean, there are less rivers with huge outflows, as well
as deep trenches to collect and accumulate this sediment.

Another sediment type of reefs is biogenic sediment. Biogenic sediment
is derived from living animal and plants. These are sediments formed
from diatoms skeletons, and skeletons of other animals and plants that have
passed through the water column. Biogenic sediments usually contain
a high level of Calcium Carbonate.

I would like to share some of my personal research on reef habitats of
the Atlantic Ocean.

I spent four years studying natural processes and the impact these had
on reef systems of Florida and the Caribbean. Part of this was the in depth
study of reef system sediments and nearby communities.

In a typical Florida reef, approximately 25% of the sediment is composed
of crushed and broken coral skeletons. Acropora was the dominant skeleton
found crushed along the reef base.

15% was calcareous algae. All the coralline encrusted bits and chunks of
rock- thing GARF Grunge here :-) 30% was from the remnant of Halimeda
skeletons. This is a calcareous macro alage that grows prolifically in
Florida Reefs. 6% were from formaniferan skeletons and diatoms
skeletons. Another 15% was composed of various mollusk shells.
Crushed oyster shells, clam shells and such. The remaining 9% was
miscellaneous debris that could not be classified and terrigenous mineral
deposits.

In a Caribbean Reef 24% was coral skeletons, 33% was from coralline
alages, 22% was from Halimeda alages, 12% was formaniferans, 8% was from
mollusks, and the remainder unclassifiable. What this appeared like
was a coarse gravel with large chunks of coral skeleton that have a loose
base of approximately 15 inches. Beneath this was a porous hardpack
of reef foundation material. This hard pack is cemented sediment that is
usually quite porous in nature.

Nearby was an Inshore Boulder community. This is a shallow (4 to 6
meter) biotope that is characterized by smooth boulders and sand and
hardpack rock.

This type of biotope has very little diversity, but was rather
homogenous in its sediment composition. Further down the was the offshore
boulder habitat. It has a higher diversity with its 6 to 8 meter
depth. It has more of the coral skeleton rubble. Its animal diversity was
about 6% higher. On the reef flat on the facing side is where I took
the sediment measurements. On the leeward side, there was a considerable
accumulation of sediments.

Many biogenic in nature. They were composed of remnants of biogenic
films of cyanbacteria, seagrasses, and plankton. It may be surprising
to many that this very mud¹ like sediment was typical on the leeward
channels of almost every reef flat visited.

Now, again, how does all this relate to the home aquarium? Coarse
sediments are very difficult for animals to inhabit. The sand grains
are cutting, and have a considerable mass that can easily crush the soft
bodied animals. Most life here tends to be tube burrowing worms, and
mollusks.

Many are considered meiofauna as they exist in between sediment partakes
as to prevent this destruction from abrasion. Finer sediments from
sandy silt to mud typically have a rich fauna. Thousands of species can be
found in healthy sheltered mud flats and grass beds. These natural
sediment beds have another role as well. That role is as a mineral
source.

In nature, marine sediments will sometimes release minerals that will
precipitate to form irregular deposits on the seafloor. In the global
ocean these deposits generally have little impact on the chemistry. This
nature of releasing minerals does play a role in a closed system.

Coral skeletons, and Halimeda is composed of calcium carbonate is
composed of calcium carbonate in the form of aragonite. While many of
the red alages, and forams have CaCO3 in the form of calcite.

Without having awful chemistry lecture flashbacks, let me say that
Calcium carbonate can exist in three forms- two of which are important to
reef systems. Those are calcite and aragonite.

So now I am back to the nature of the sand bed of the home aquarium.
Typically, folks dump in a uniform size gravel of aragonite based sand. As
you can surmise, this is rather inadequate if you wish to support a large
diversity of life within your sediment. This can be overcome in a variety
of methods. The least effective- yet the easiest is to layer your sand in
sizes.

Using a fine sand and a medium sand and a coarse sand you can replicate
the diversity of sediments to a limited extent. Many folk like to
layer these is distinct layers, and even separate with screening.

I have found that overtime, energy from water flow, chemical processes,
and any infaunal migration will thoroughly mix these layers. So, I have had
great success dumping all my sediments into a container and mixing and
adding to the tank. Next one will ask about depth. Well, as I said,
on a Caribbean reef the sand is loose to 15 to 20 inches.

Now since most of us don¹t want a sand tank with a few corals- we want a
reef tank with some sand- what are we to do? I say at least 6 inches.
Go more if you can give up the space. There are many tricks to hide the
substrate later to make the tank more aesthetically pleasing. Another
more complex method is to have a mixed sediment system. This is
involves using a sump and or refugium as well.

Rather than go into great detail and stir up controversies, I will say
this: Refugia with seagrasses and mangroves serve many useful purposes. As
a habitat for small shrimp, fish, mollusks, etc. And as a means to filter
the aquarium. When I say filter- I also include mechanical and biological
filtration.

Seagrasses in nature act as a baffle for sediment suspended in water,
and will draw these sediments down to their bases. In a properly
flowing system the seagrasses can serve much the same purpose at home.

In a sump, you can also add a softer substrate to allow for the greater
diversity of animals. Wait! Someone is bound to ask why? Why do we
want to increase diversity if our current NNR or other systems seem to
work?

My initial reply usually involves a species list of what is in my
systems...... animals like seapens, breeding Flame Scallops, and
filterfeeding gorgonians. With the added diversity of animals and plants
your system can better sustain your corals and fish.

A bit off the scope, this type of system will pave the way for going
skimmerless. and heavy feedings. Both of which I recommend.

To answer some of the many questions I see on the lists and
message boards. Live sand will not form from dead sand. Period.
Louis Pasteur proved the world wrong on spontaneous generation, and it wont
happen in your reef tank. No matter how good the live rock is, it wont
provide what is necessary for a healthy sand bed.

On shipping live sand.

As I said sand is rough Its cuts, it grinds. And have you ever lifted 50
pounds of it?!? Imagine being a soft bodied annelid or a think
shelled mollusk. And being grated, smashed, and smooshed by the sand.
And THEN handled by the airline luggage handlers or FEDEX !!!!!

Its a miracle any life makes it at all. In my opinion the shipment of
living animals IN sand is a poor substitute at best. Its best to
collect them directly- not an option for many. So that leaves us with
purchasing cultured animals that can populate sand beds. And a few outfits
currently do this, and I hope more are developing this.

Well folks, that is about it. I hope I have broadened your outlook about
what sand beds can do if applied properly. I will be happy to answer any
involved questions via email at SeaMuskrat@aol.com. Thank you.

Questions

I wanted to know what the speaker thinks of collecting from the Salt
Water Bays on the Gulf Coast... ah live sand and or animals?

I have collected from the Gulf Shore of Florida many times. I
have found the quality of infauna to be excellent for a reef
system. As for the sand, I suggest you sieve through it to separate
the animals from the sediment, and transport separately.

Normally we buy live sand that is scooped up from the ocean floor around
reefs. That sand is pretty homogeneous in particle size. Would our tanks be
better off with a wider distribution of particle sizes?

In my opinoon, yes. Mixing of many particle sizes will allow for
greater diversity to take place within sand bed. This is quite
easily done, as there are at least three grades of sand avaiable in most
LFS. Of course- you still have to 'seed' the proper animals to take
advantage of this.

How is the live sand harvested and how is the natural reef impacted?

For research purposes I have collected live sand, in pint size bags,
while keeping them completely underwater. This allows for a
segregation of layers- as I do not mix surface layers with bottom layers,
etc. But it is NOT commercially viable- as it took me hours to
collect a mere 50 pounds of sand. As for impact to reefs- new sand
is formed daily from fish, inverts and waves. I imagine it
is minimal if done responsibly.

The cemented sediment, what is it "cemented with?... detritus?
and how do we prevent it?

In nature- the cemented sediment was actual bonding of various ionic
constituents. It was a beneficial aspect. It acted liek a deep
denitrification sponge beneath the sediment. It does not have an
analogous counterpart in a home system. As for preventing it in a
home system- I have never had to. I keep a variety of fish
and inverts that seem to keep the sand from becomming cemented. I have
not done anything special to prevent this from ocurring.

What "sand sifting" animals are to be avoided in the reef tank?

My number one critter to avoid is the Horseshoe crab. Awesome
animals, just not suited for home use. As for others- some of the
more specific feeders. Many basket starts and crinoids due some excellent
sediment sifting, but they are also very finicky about other habitat
requirements. I have a number of seapens that are amazing at mixing
layers of sediments. They can dig down 10 inches in under 15 minutes,
swell up and mix the sands. But they require a nearly continual dose of
live foods. So, I woudl say those animals that cannot be easily
maintained because of size, diet of lifestyle.

"If you have a 48" deep aquarium would you try and put 15"+ of
sand in it to replicate a reef enviorn.? If so are there any dangers of
building toxic gases, etc.?"

Heeheehee. I have doen this- to some extent.
I had a test tank that I was using to display the layering of sedimenta.
It had wave action on top, and over time, you could see distinct layers
of sediemnt based on size. It was naturally collected sediment,
although in the 'tank' portion, we kept no aninmals. I never
noticed any outgassing of significant nature. When we took the exhibit
down, it has a slight odor to it. Again- if its healtly it should
naturally take care of all breakdown processes. This topic can be more
fully covered via email. Just send me a note and I will be more than
happy to provide more details.

If we use different layers of sand to diversify particle size, should
screens be placed between the layers to prevent burrowing animals from
churning and mixing the sand as you alluded to in your talk?

No- the mixing is good.

What do think the composition of a 6" sand bed should contain.
ex, clay olithic sand coarse coral tc.?

Well, some % of oolitic sand, some 'fine' sand, and some crushed
coral. Thsi is three grades that can be found at most LFS. I would
stay away from clays and silts and muds in MAIN tank. I have foudn they
require a special sump to prevent them from stressing the organisms
because of the fine particle size and the high energy levels in the tank.
The suspended particles will cause corals to close up.

You've talked mainly about white sand Is Black Sand a viable thing for
an aquarium?

I am not familar with the product you mean specifically. Dyded
black sand is NOT good. As for natural black sand- as in volcanic
ash, I would shy away from it from potential mineral release. I dont knwo
for sure- but I suspct black sand could contain many undesirable
compounds.

In a deep sand base how to we keep from developing dead spots, and how
deep do you recommend?

In a home tank- 6 inches minimum. 8 to 10 if you can 'afford' the
sapce. It DOES take away from water volume, so you have to make a
choice. Another option is to do 5 to 6 in tank, and have a
sump with 10 inches. As for dead spots- I dont do anything. I have
not had them as a significant problem. They exist in nature and in tanks.
With a healthly system, it should not be an issue.

What about all this talk about "MUD" filtration, usefull or hype?

Hmm. What 'type' of MUD filtration?
The mud system as advertised to be used without a sand bed, and releys
heavily on Calupera is IMO bunk. I have tested this 'miracle mud'
and its terrigenous sediment from the So Cal Mountains. So its not marine
in origin, and as such has no special properties. I do feel that mud liek
sediments are beneficial. And that is explained in great detail in June
and July FAMA issues.
PS- email me on that as well.

Do you think we have enough cultuered species so that we don't need
natural live sand anymore?

NO!!!!!!!! SM I WISH we did.

Is there a reference we can look at to get addresses and phone #'s of
suppliers?

I can make one up and have it posted on the website. I presume that is
ok.

Less tna 6" of sand, say 2-3", worse than just a thin layer used
for decrative effect?

Generally no. Even a small sand bed will have an important biologic
function. It will not support a great diversity of infauna- but it will
do some denitrification, as well as provide a habitat for small
crustaceans, etc.

Since most of us cannot collect How can we get the "Live Sand" if
the creatures are killed in shipping?

Short of separate shipment of animals colelcted from sand, I have no
good answer. Packaging of animals seprate of the sand will have
the best odds of survival and you know what you are placing in
tank. That seems to be the best way at this point in time. I
have heard that some have developed better shipment methods, but have no
experience with them.

If one adds more sand to their tank how should one do it?Remove all
detrius?Mix it throughly?

Add it above existing sand. I prefer to leave detritus. Dont knwo why-
just a thing I do. DONT mix it. Allow the sediments to sort
naturally. Since that was brought up- I do NOT liek the idea of
mixing sand once its in the tank. I do mix sand sizes in a new
system prior to adding to system. But oince they are in the tank-
allow natural processes (energy transfer and animals) to mix for you.

Is the live sand that we now purchase from our LFS of any real
value?

I cannot say. At my LFS its worthless. But there is SOME good
live sand out there.

What in your opinion is the best place to get live sand? Mail order, lfs
etc

Tough one to qualify. LFS get it from mostly the same sources
that mail order stores do. Some MO stores collect their own. If you
can get it with minimal handling- it will be better. So, collecter
to wholesaler to door os best. The more intermediate steps, the more time
passes and the more damage.

Are commecially available sand bed boosters worth it?

I KNEW that was coming........
In clinical trials I found no difference in system susing 'vital'
products and systems without.

Would collecting sand from local areas including non tropical areas be
ok?

Yes and no. I have a tropical tank with many animals from Long Island
Sound. The more temeprate you go the more problems you will
have. Coller climate animals wont adapt well to tropical tank
temps, and you run risk of introducing unwanted predatorsa etc. But
if you collected in summer, from local waters (legally or course) and set
this up for culture. You could then harvest works, clams, and
crustaceans that come from it- without fear'of intriducing any
contaminants.

Do you know of anyone that ships the animals separate from sand?

Yes, Inland Aquatics sells a detrivore kit that is useful for this
purpose. I believe the site www.Reefreviews.com has a catalog and
more info on live sand critters for sale

When one adds sand to a new system.. do you recommend any commercial
cycle products, grunge things etc?

I dont add any commercial products to any of my systems. However
for a new system- you must allow it to cycle. And it will cycle faster if
you 'seed' it with material from an esta=blsuhed system. I use my
own GARF GRUNGE liek material- its just my own reef rubble from my
ssytems. Same thing, more or less. I would add the living animals
to the system as soon as the rock is cured.

I think some wanted to know if "cycle helpers" actaually help?

Well, without starting a whole new chat..... I have looked at
BioZyme, FritzZyme, Cycle Vital.... And others. NONE do what
they claim on package. Some help. To some level. Lets leave it at that
(for now).

What if anything can one look for in "good" live sand that cannot be
found "bad" live sand?

Polychaets, and annelids. And small bivales. Liek Macomas (duck clams)
or Gem shells. Anything soft and crushable. If those are
present (and you most certainly WANT them) then you have excellent sand.
PS Hopefully the larval forms of many of these will survive in
your sand ansd grow up to populate it later.